1. Field of the Invention
The present invention relates to an image pickup apparatus and a signal value correction method that by a simple configuration make it possible to quickly and accurately correct the variation in signal values caused by a color array for color filters of an image pickup element and the variation in signal values caused by a structure in which multiple pixels share a specific circuit element.
2. Description of the Related Art
CMOS (Complementary Metal Oxide Semiconductor) image pickup elements exhibit low power consumption, and are used in a variety of portable image pickup apparatuses such as digital cameras and mobile phones.
In CMOS image pickup elements, a technique in which multiple pixels share a single amplifier is widely used as a technique for reducing the number of transistors required on the substrate.
In particular, an image pickup element that has color filters in a Bayer array (GR/BG) and a sharing structure for sharing a single amplifier on a 2×2 pixels basis, exhibits a good matching because the repetition period of the Bayer array (2×2) is equal to the repetition period of the amplifier sharing structure (2×2), and therefore, the image pickup element is very commonly used.
Japanese Patent Application Laid-Open No. 2008-288649 discloses a configuration in which correction is performed using a vertical-line correction parameter for multiple lines in view of an amplifier sharing pattern.
Japanese Patent Application Laid-Open No. 2000-78474 describes a CMOS image pickup element that achieves space saving by sharing an amplifier on a vertical 2×horizontal 2 pixel basis.
Japanese Patent Application Laid-Open No. 2007-142697 discloses a configuration in which four pixels around a pixel of interest separately have color-mixing correction parameters, in order to respond to the pixel-by-pixel difference of the color-mixing rate, resulting from the asymmetry of the aperture of each pixel.